THE weather is preparing to go wild, and will wreak havoc and death around the globe later this year. An El Niño, a splurge of warm water in the Pacific Ocean, is coming. It will unleash floods in the Americas, while South-East Asia and Australia face drought. Yet little is being done to address these consequences.

An El Niño begins when warm water near Indonesia spreads eastwards and rises to the surface of the Pacific. The warm water carries rain with it, so El Niño takes rain from Asia and Australia and dumps it on the Americas (see “Rising waters“).

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The effects can be deadly. A big El Niño in 1997-98 killed 20,000 people and caused almost &dollar;97 billion of damage.

Meteorologists contacted by New Scientist all expect an El Niño at the end of this year. And it looks like a big one, says Wenju Cai of CSIRO, Australia’s national research agency, in Melbourne. The more heat in the Pacific, the bigger the El Niño, and right now, 150 metres below the surface, a ball of warm water is crossing that ocean. “It’s huge,” says Cai.

Most El Niño researchers say forecasters are being too conservative. “One thing I hear over and over again is ‘we do not want to create a panic’,” says Timmermann. There is a reason&colon; forecasting a big El Niño would cause a spike in food prices. “But it may be better to have this reaction at an early stage, when farmers can still adapt, rather than later.”

The good news is that El Niño is a known quantity. “We already know what happens when a big El Niño hits,” says Zafar Adeel of the United Nations University in Hamilton, Canada. That means vulnerable populations can be identified and emergency plans put in place. But not everywhere has a plan.

We already know what happens when a big El Niño hits. Now vulnerable populations must be identified and emergency plans put in place

California, which faces floods, is well prepared for emergencies and has water rescue teams, says David McEntire of the University of North Texas in Denton. But Central and South America are more vulnerable (see “In the firing line“) and it is unclear what will happen in Asia and Australia (see “Monsoon disruption“). India has invested in water storage in case of drought.

A big El Niño does not have to be a disaster. Impacts like shifting fish stocks and changes in rainfall can be handled, or even turned into benefits, if people are prepared for them. “But you need that trigger saying ‘yes it’s going to be a big one’,” says Zafar.

Monsoon disruption

Asia and Australia will see less rainfall as a result of El Niño, leading to drought and wildfires. But many impacts depend on how El Niño affects the monsoons, which is hard to predict.

“There is no other phenomenon that can influence the monsoons like El Niño,” says Krishna Kumar of the Indian Institute of Tropical Meteorology in Pune. If it weakens the Asian monsoons, it will threaten the food supply of billions of people.

Most El Niños weaken east Asian monsoons, but the Indian monsoon may survive. El Niños have caused the Indian monsoon to fail, however the 1997-98 El Niño didn’t, despite being the biggest on record (Science, doi.org/fj7cbx). Kumar says the coming El Niño looks similar to the 1997-98 event, so India might be lucky.

Rising waters

The western US faces storms and floods from an approaching El Niño.

The sea level along California’s coast may rise 30 centimetres, and then be pushed even higher by storm surges, says Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colorado. Extra water may sound good, because California has been hit by a severe drought. But the raised seas may combine with heavy El Niño rains to cause devastating floods, as happened to the San Francisco area in 1997-98.

El Niño also brings warmer weather, which melts ice. In 1997, extra river water in North Dakota and Minnesota may have contributed to the worst flood of the Red river since 1826.

In the firing line

When El Niño arrives, Central and South America face a mix of storms, floods and droughts.

These countries are more vulnerable to the effects of El Niño than the US, partly because they have less money. “Poverty is a major cause of vulnerability,” says David McEntire of the University of North Texas in Denton.

However, more-developed regions are not always better off, says McEntire. Development causes its own problems, such as greater use of dangerous chemicals that can escape during disasters. And wealthier regions produce less of their own food, so can run short quickly.

As a result of all these issues, most countries in Latin America have become more vulnerable to El Niño, says Rodney Martínez of the International Research Centre on El Niño in Guayaquil, Ecuador. Even though many have El Niño response plans, the risks have grown thanks to population increases and crops being planted in high-risk zones. Such countries can also struggle to give each area a warning that is local enough.

This article appeared in print under the headline “Sitting ducks in coming storm”